The following is a summary of “Microvascular Inflammation of Kidney Allografts and Clinical Outcomes,” published in the October 2024 issue of Nephrology by Sablik et al. 

Researchers conducted a retrospective study on the impact of microvascular inflammation on kidney allograft outcomes. 

They conducted a cohort study involving kidney-transplant recipients from over 30 transplantation centers in Europe and North America who underwent allograft biopsy between 2004 and 2023. They classified biopsy specimens based on the 2022 Banff Classification, which includes 2 new diagnostic categories: probable antibody-mediated rejection and microvascular inflammation without antibody-mediated response. They assessed the relationship between microvascular inflammation phenotypes and allograft survival and disease progression. 

The results showed that 16,293 kidney-transplant biopsy specimens from 6,798 patients were assessed. Microvascular inflammation phenotypes were identified in 788 specimens, 641 of which were previously classified as no evidence of rejection. Compared to patients without rejection, the hazard ratio (HR) for graft loss was 2.1 (95% CI, 1.5-3.1) for those with microvascular inflammation without antibody-mediated response and 2.7 (95% CI, 2.2-3.3) for those with antibody-mediated rejection. Patients with probable antibody-mediated rejection had a higher risk of graft failure beyond 5 years (HR, 1.7; 95% CI, 0.8-3.5). Those with either microvascular inflammation phenotype had a higher risk of transplant glomerulopathy progression. 

They concluded that microvascular inflammation in kidney allografts includes distinct phenotypes affecting disease progression and outcomes. Their findings supported the use of additional rejection phenotypes to standardize diagnostic approaches for kidney allografts. 

Source: nejm.org/doi/full/10.1056/NEJMoa2408835